During a sermon delivered at Proclaim 16, the NRB International Christian Media Convention, Saddleback Church pastor Rick Warren encouraged attendees to remember that a Christian leader's "greatest ministry comes not out of your strength but your weakness."

On Wednesday, Warren addressed the audience made up of Christian broadcasters, pastors, and others gathered at the Gaylord Opryland Resort & Convention Center in Nashville, Tennessee.

After being introduced by Hobby Lobby owner Steve Green, the megachurch pastor shared his own experience as an evangelist and revealed how God has faithfully kept his promises throughout his life: "In every opportunity of my life, and in every crisis of my life, God has given me a promise," Warren said.

He highlighted eight specific promises the Lord had given him in Scripture and revealed how each promise has been fulfilled throughout his 45 years in ministry.

Warren first shared how God told him to enter into full-time Christian ministry after he was converted while in high school. After marrying his wife, Kay, following just two dates, God told him he was to attend seminary instead of plant a church.

Although he and his wife are now celebrating 40 years of marriage, Warren recalled how the first two years were extremely difficult -- "But divorce was off the table. Murder, yes, divorce, no," the pastor joked.

During this difficult time, God gave him Galatians 6:9, which urges followers of Christ not to grow tired of doing what is right. That verse -- and marriage counseling -- saved their marriage, the pastor said.

"You might think you can't afford counseling -- You can't afford NOT to have counseling," the pastor advised married couples.

Later, God told Warren he should pastor a "missionary-sending church" - known today as Saddleback Church. The church began to grow at a rapid pace, and because he had no staff and was "doing it all" on his own, the pastor soon suffered burnout and severe depression.

Jesus once again proved faithful, and showed Warren He would build His church. However, the Lord promised He would provide it with "pacing growth": "We overestimate what we can do in a year; we underestimate what we can do in 10 or 20 or 30 or even 40," Warren said.

The darkest moment in both his and Kay's life, however, was when their 27-year-old son, Matthew, took his own life after a lengthy struggle with depression and mental illness.

"He came to me one day with tears in his eyes and said, 'Dad it's pretty clear the Lord isn't going to heal me.' Every day, his brain said, 'Die,'" Warren said. "Your illness is not your identity, and your chemistry is not your character."

The pastor shared how his small group supported his family during that time, and expressed hope that someday, he will be reunited with his son in Heaven. Warren said that amid the pain, God gave him the promise given to David when his infant son died.

"I can't bring him back to life," Warren said of David's words in II Sam. 12:23. "He cannot come back to me, but one day I will go to him."

After Matthew's death, the letters that meant the most were not from "Kings and ambassadors and presidents," but from people whom the young man had led to Christ. At the time, Warren wrote in his journal, "In God's garden of grace, even broken trees bear fruit."

Everyone is broken, he said. "Pain can obscure God's promises, but it can't nullify them."

Based on his experiences, Warren said he can confidently tell others that a Christian leader's "greatest ministry comes not out of your strength but your weakness."

"We minister to people out of our weaknesses, not our strengths," he said. "Base your ministry not on your talent; base your ministry not on your abilities, not on your cleverness, not on your giftedness. Base your ministry on the promises of God."

After a brief prayer, singer-songwriter Michael W. Smith then took the stage and led the gathering in singing a worshipful rendition of the hymn "Agnus Dei."

According to its website, the NRB's Proclaim 16 is a multi-day convention that "connects, equips, and edifies thousands of Christian communicators - from broadcasters to producers, writers to publishers, managers to pastors, artists to consultants."

"You will hear outstanding internationally known speakers and artists, have the opportunity to attend numerous networking events, and receive helpful industry insights," reads the site.

Next year's convention will be held February 27-March 2, 2017, in Orlando, Florida.